Commercial package and method and apparatus for making the same



March 27, 1962 ,RUMSEY, JR 3,026,656

COMMERCIAL P AGE AND METHOD AND APPARATUS FOR MAKING THE SAM Flled Apr1l 22, 1958 5 Sheets-Sheet l llflllllllllilllllll|llllhllMilllllllllllllll INVENTOR HEQBEE 7' Ell/WE) JE- BY7%)2 Qua and. 1 K

ATTORNEY March 27, 1962 H. RUMSEY, JR 3,026,656

COMMERCIAL PACKAGE AND METHOD AND APPARATUS FOR MAKING THE SAME Filed April 22, 1958 3 Sheets-Sheet 2 48 M Aw Fla ,2

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: BY //,e5,e7 ems/5r J/Z.

ATTOENE Y March 27, 1962 H. RUMSEY, JR 3,026,656

COMMERCIAL PACKAGE AND METHOD AND APPARATUS FOR MAKING THE sAME Filed April 22, 1958 3 Sheets-Sheet 3 E: i C: a Q: 4/ 40 ATTORNEY United States This invention relates to an improved commercial package and method and apparatus for making the same and has particular relation to a package wrapped in sheet material which is at least partially evacuated.

Food products are frequently packaged in transparent sheet material, such as the synthetic resins or plastics, in a manner to improve the appearance thereof, and it has been found that by removing the air or a large portion thereof from the package the product will be protected and preserved for a relatively longer period of time.

It is an object of the present invention to provide an improved commercial package wrapped in sheet material and an improved method and apparatus for making the same wherein the air or a substantial portion thereof is removed in an improved and effective manner and the package is thereupon effectively sealed so that the air will not re-enter the package at the point of extraction.

A further object is the provision of an improved package, method, and apparatus of the above character wherein the packaging procedure is simple and inexpensive and is not complicated by the use of cumbersome machinery or the performance of multiple or intricate operations.

Another object of my present invention is to provide an improved method and apparatus for extracting air from a package while it is being wrapped in sheet material which lends itself to many different types of wrapping operations and does not require specific wrapping operations, such as the twisting of projecting end portions of the wrapping material.

In the accompanying drawings, FIG. 1 is a plan view of one form of package embodying my invention;

FIG. 2 is a similar view showing the first step in wrapping the package;

FIG. 3 is a similar view showing a further step in the wrapping of the package;

FIG. 4 is a sectional view in the direction of the arrows on the line 4-4 of FIG. 3;

FIG. 5 is a plan view similar to FIG. 3 showing a modified form of package embodying my invention in partially-wrapped condition;

FIG. 6 is a cross-sectional view in the direction of the arrows on the line 6-6 in FIG. 5;

FIG. 7 is a plan view of a further modified form of package in which a different type of sheet wrapping material is employed;

FIG. 8 is a longitudinal sectional view in the direction of the arrows on the line 88 of FIG. 7;

FIG. 9 is a perspective view of a further modified type of package embodying my invention;

FIG. 10 is a fragmentary sectional view showing the package of FIG. 3 in cross-section having applied thereto the apparatus that may be used in extracting air from the package;

FIG. 11 is a View similar to FIG. 10 showing the manner in which the package is sealed in the area through which the air is extracted;

FIG. 12 shows the lower end of a modified form of apparatus indicating one method of forming an aperture or air passage in a layer of the wrapping material;

FIG. 13 is a side elevational view of apparatus that may be employed in extracting air from the package;

FIG. 14 is a longitudinal sectional view of the apparatus;

atent FIGS. 15 and 16 are cross-sectional views in the direction of the arrows on the lines 15ll5 and I616 of FIG. 14 showing the valve construction;

FIG. 17 is an enlarged detailed view in perspective showing the spacer member forming part of the improved apparatus;

FIG. 18 is a longitudinal sectional view of a modified form of apparatus which may be used in forming an air passage or aperture in the wrapping material; and

FIG. 19 is a detailed view in perspective showing the mounting of the heat-piercing member of the apparatus shown in FIG. 18.

In carrying out my invention I wrap the package contents in packaging material including a sheet of wrapping material so as to provide overlapping layers of the packaging material with one of the overlapping layers having a surface exposed at the exterior of the package, and the other layer disposed inside the package. The overlapping layers are formed with proximately-spaced edge portions which provide proximately-spaced passages offset with respect to each other and affording communication between the two surfaces of the respective overlapping layers. Thereafter, suction is applied to the overlapping layers in a confined area encompassing both of the air passages so as to separate them from each other and so as to withdraw entrapped air from inside the package past the air passage of the inner layer, thence between the layers and out past the air passage of the outer layer. Finally, while continuing to apply suction thereto, I initiate the sealing of the overlapping layers and then complete the sealing in the area adjacent the air passages so as to prevent the re-entry of air into the package.

Packages embodying my invention may be used for many different types of products, but are particularly useful in the packaging of products, such as food products which are protected and preserved for longer periods of time when the air or at least a portion of the air is removed from the package. Thus my invention may be used for the packaging of meat products of various types, dairy products, such as cheese or butter and the like.

In the accompanying drawings I have illustrated the package as applied to a sliced, chopped, or molded meat product.

Referring to the form of package shown in FIGS. 1 to 4, inclusive, the package contents 20, which as mentioned above is a meat product, is encased in packaging material consisting of a sheet of flexible, transparent plastic material 21, which is substantially impervious to air and will not adversely alfect the contents of the package. The wrapping material is of the type which will seal or adhere together when contacting surfaces thereof are subjected to heat and pressure. It is also preferably of the type which will shrink when subjected to heat lower than its fusing point. For this purpose I prefer to employ pretensi-lized polyvinylidene chloride and rubber hydrochloride. Various plastic wrapping materials of this type are available having plasticizers which will become tacky and will thus seal together when heated to a temperature lower than the boiling point of water, i.e. between F. and 212 F. Particularly useful for this purpose is the po-lyvinylidene chloride wrapping material sold commercially under the trademark Cryovac by the Cryovac Company, Division of W. R. Grace & Company, of Cambridge, Massachusetts, the polyvinylidene chloride wrapping material sold commercially under the trademark Saran by Dow Chemical Company, of Midland, Michigan; and the rubber hydrochloride wrapping material sold commercially under the trademark Pliofilm by B. F. Goodrich Company, of Akron, Ohio, or other examples of wrapping materials of this type that may be used.

The wrapping material is wrapped around the package contents as previously indicated so as to provide overlappinglayers. As an example, a sheet of the wrapping material 21 may be wrapped around the product in the manner shown in FIGS. 2, 3, and 4. Thus the package contents 20 is placed near the center of the sheet as shown in FIG. 2 and the two longitudinal edge portions of the sheet are folded inwardly over the package contents in superimposed relationship providing overlapping layers as shown most clearly in FIG. 4. The end portions of the sheet project beyond the ends of the package contents, as shown at 24, and these are heat-sealed in closed relation as indicated at 25. Under the packaging procedures shown in FIGS. 1 to 4, the sheet wrapping material is ultimately shrunk around the package so as to eliminate wrinkles and so as to cause the packaging material to tightly embrace the package contents. I accordingly form the heat seals 25 at a spaced distance from the end of the package contents 20 as shown in FIG. 3 so as to allow for this shrinkage.

The overlapping layers 22 and 23 are formed with spaced edge portions providing proximately-spaced air passages. These edge portions and air passages may take the form of apertures 26 and 27, which may be pre-formed in the sheet in the manner shown in FIG. 2 so that they will be properly spaced from each other when the layers are folded into overlapping relationship or they may be formed in the overlapping layers during the wrapping operation. As will be later seen, the spaced edges and air passages may simply constitute the end edges of the overlapping layers and the space beyond the edges. At any rate, when the packaging material is wrapped around the package contents in the manner shown in FIG. 3, the two air passages 26 and 27 are proximately spaced from each other.

The aperture 27 in the outer layer is exposed at the exterior of the package, and the aperture 26 'in the inner layer 22 is disposed at the interior of the package. The spacing between the air passages may be varied. Where the spacing is increased, a higher degree of suction must be applied to the exterior of the package in withdrawing the air from the interior. Where the spacing is decreased, a lesser degree of suction may be applied. I have found that very satisfactory results are obtained where the spacing between the air passages is approximately one inch or a little less.

After the package has been partially wrapped in the manner shown in FIG. 3, suction is applied to the outer surface of the overlapping layers in a confined area encompassing both of the air passages as indicated in dotted lines at 28. The suction is preferably applied in the manner indicated in FIG. so as to cause a slight separation between the layers in the confined area and between the inner layer and the contents of the package, with the result that the entrapped air from all portions of the inside of the package is withdrawn through the inner air passage 26, thence between the two layers and outwardly through the outer air passage 27. Then while continuing to apply the suction to the confined area of the package, the overlapping layers are sealed together in the area of the air passages 80 as to prevent re-entry of the air through the air passages; and the entire sheet of wrapping material is subjected to sufficient heat to cause it to shrink around the package contents, eliminating wrinkles and presenting a smooth, attractive appearance. The shrinking and the heat also cause the remainder of the two overlapping layers 22 and 23 to become heat sealed together.

The application of the suction may be accomplished by means of suitable apparatus, for example by means of the apparatus shown in FIGS. 10 and 11 and 13 to 17, inclusive; and the heating, shrinking, and sealing may be accomplished by hot air or by immersion in hot water of a temperature in. excess of 180 F., as indicated in FIGS. 10 and 11.

The apparatus for applying the suction illustrated in FIGS. 13 to 17 comprises a tubular casing 30, which provides a vacuum chamber 31 in the interior thereof. Extending transversely of the vacuum chamber so as to divide it into an upper and lower portion is a partition 32 having a central aperture 33 controlled by a valve and through which communication may be had between the upper and lower portions of the vacuum chamber. The partition may be suitably held in place in the casing as by screws 34, and it is preferably gasketed on one or both surfaces as shown at 35 by a suitable rubber or plastic material to prevent leakage.

The lower end of the casing is formed with an orifice 36, which is adapted to be placed against the surface of the package to apply suction thereto. For this purpose I provide a flexible resilient tubular gasket 37 disposed around and projecting beyond the lower end of the casing and held in place by a ring clamp 38. The flexible gasket 37 will conform to irregularities in the package surface and will provide a better seal between the vacuum chamber and the package. The diameter of the orifice and of the gasket 37 should be suflicient to encompass the spaced apertures or air passages 26 and 27, as indicated in dotted lines at 28 in FIG. 3.

The upper portion of the vacuum chamber is provided with a suitable outlet duct 39, which is connected to a vacuum source so as to develop the desired suction. The top of the vacuum chamber is closed by a suitable cap 40, and I provide a bypass in the form of an aperture 41 extending through the center of the cap for conmeeting the interior of the vacuum chamber with the atmosphere. Suitable control mechanism is provided for the apparatus in the form of reciprocating rod 42 having an operating handle 43 and surrounded by a helical spring 44 extending between the handle and the top of the casing, as shown, to normally maintain the rod in elevated position. The central portion of rod 42 is cylindrical as indicated at 45 and is of a size to form a sealing fit with the aperture 33 in partition 32 and with the aperture 41 in cap 40. Thus the upper end of the cylindrical portion 45 serves as a valve for aperture 41 and the lower portion serves as a valve for aperture 33. Immediately above and below the cylindrical portion 45 are flattened stems 46 and 47 of reduced cross-sectional arrangement. When the stem 46 is disposed in aperture 41, the bypass is open and the upper portion of the chamber communicates with the atmosphere. When the stem portion 47 is in registry with aperture 33, then aperture 33, is open and the upper and lower portions of the vacuum chamber communicate with each other. The valves and stem portions are so arranged that when the spring elevates the rod to its normal position, valve 45 will close aperture 41 and aperture 33 will open. When manual pressure is applied to the handle 43 to shift the rod downwardly to the position shown in FIG. 14, the bypass aperture 41 will be open and aperture 33 will be closed.

Associated with the lower end of the rod 42 is the spacer member 48. When the rod is in its normal elevated position, the spacer member is positioned inside the vacuum chamber or casing. When the rod is depressed so as to open aperture 41 and close aperture 33, spacer member 48 is projected outwardly through the orifice so as to space the apparatus away from the surface of the package to which it is applied. The spacer 48 also serves to exert pressure against the overlapping layers of the wrapping material in the area of the voids or apertures so as to help seal them. The particular form of the spacer member may vary. Very satisfactory results have been obtained by using a U-shaped member as shown mountedv on the support 49, which is threaded to the end of the rod 42. The relative position of the spacer member 48 may be adjusted on the end of the rod due to the threads, and it may be locked in adjusted position by the nut 50.

In using the apparatus of FIGS. 13 to 17 in applying suction to the overlapping layers of the wrapping material of the package, the apparatus is connected by tubular duct 39 to a suitable source of vacuum with the handle in elevated position, the lower end of the apparatus is applied to the area of the package indicated in dotted lines in FIG. 3, as shown in FIG. 10. The gasket 37 provides a sufficient seal between the vacuum chamber and the outer surface of the package and confines the suction to the indicated area. Since the handle 43 is in elevated position, aperture 41 is closed by valve 45 and aperture 33 is open. The result is that a vacuum or reduced pressure is developed in the lower portion of the vacuum chamber and the two overlapping layers will be caused to separate and to separate from the package contents as indicated in FIG. 10. The entrapped air inside the package will be drawn outwardly through aperture 26, thence between the layers and outwardly through aperture 27.

While continuing to apply suction to the surface of the package, the wrapping material is subjected to heat so as to cause it to shrink and so as to cause the overlapping layers to seal together and the area of the overlapping fiaps adjacent the apertures is subjected to pressure and to heat to seal them together. This may be accomplished in the manner shown in FIG. by inserting the package with the vacuum apparatus still applied thereto into a container with water therein heated to a temperature in excess of 180 F.

In FIG. 10, I have shown a container 52 having heated water 53 therein. A spacing plate 54 may be arranged at the bottom of the container so that when the package with the apparatus applied thereto is inserted in the container, the water will barely cover the upper surface of the package and surround the flexible housing at the lower end of the suction apparatus. When the hot water contacts the wrapping material, it uniformly heats all portions thereof and causes it to shrink so that the sealed ends 25 are pulled in against the ends of the package contents, the wrinkles in the wrapping material are eliminated, and the package presents a smooth, attractive appearance. In this connection, the heat reinforces the sealed ends 25 in the area between the heat seal and the package and prevents rupturing thereof during shrinkage. The shrinking of the wrapping material causes the overlapping layers to exert pressure against each other, which when combined with the heat causes them to heat seal together. Simultaneously with this operation, the operator manually depresses the handle 43, causing the spacer 4% to engage the overlapping layers in the area of the apertures and to press them together. Further lowering of the handle separates the end of the suction ap paratus from the package so that the hot water rushes in, causing sealing of the overlapping layers in the area of the apertures. The lowering of the handle to the position indicated in FIGS. 11 and 14 opens the aperture 41 and closes the aperture 33, with the result that the lower portion of the chamber 31 is no longer subjected to vacuum and assumes atmospheric pressure. Under the circumstances the Water will not be sucked therein. The apparatus and package can then be withdrawn from the container and the package is complete, ready for storage and shipment.

The complete package assumes the appearance shown in FIG. 1 and presents an attractive commercial article. The overlapping layers are sealed together including the area surrounding the air passages or apertures and accordingly the package is sealed and air cannot re-enter the package. Due to the absence of a large portion of the air from the interior of the package, the contents will be preserved for relatively longer periods of time.

Instead of arranging the air passages in overlapping layers of a sheet of wrapping material, I may provide overlapping layers of other packaging material having air passages therein. Thus in FIGS. 5 and 6 I have shown a package construction in which the overlapping layers consist of one layer of a sheet of wrapping material and a layer provided by a label or a supporting or reinforcing board. The package of FIGS. 5 and 6 comprises package contents 20 having a label or reinforcing board 55 applied to one surface thereof. The package contents and label are encased in a sheet of wrapping material 56 similar to the sheet of wrapping material 21 used in the first form of my invention. In other words, the sheet of wrapping material 56 is of the type which will shrink when subjected to heat lower than its fusing point and will seal together when contacting surfaces are subjected to heat and pressure.

The sheet 5-6 is wrapped around the label and package contents so that longitudinal edge portions are overlapped on the undersu-r face of the package as shown at 57, and the end portions are heat sealed together as shown at 58. Since the wrapping material is subsequently shrunk around the package contents, the heat seals 58 are preferably spaced from the two ends of the package contents. The label or reinforcing board 55 is made of a material or is coated with a material which will seal to the sheet wrapping material '56 when beat and pressure are applied thereto. Thus it may be made of the same material as the sheet material or it may be made of cellophane or fiberboard and coated wit-h thermoplastic material.

In this form of package the superimposed or overlapping layers comprise the outer layer 59 of sheet material which is exposed at the exterior of the package and the inner layer 55 in the form of the label or reinforcing board disposed inside the package. The outer layer is provided with an aperture 60 extending therethrough which provides an edge or air passage which is spaced from the two side edges 61 of the label or reinforcing board. The side edges of the label or reinforcing board provide the edge and the air passage for the inner layer.

After the package has been partially wrapped and is in the condition shown in FIG. 5, the lower end of the suction apparatus is applied thereto in the area indicated by the dotted line 23 so as to encompass both the aperture 60 and the voids provided by the two lateral edges 61. The suction will cause the layers to separate from each other and also to separate sufficiently from the package contents with the result that the air from inside the package will be Withdrawn past the edges 61 between the layers 55 and 59 and outwardly through the aperture 60. The package is then subjected to heat as by immersion in hot water as shown in FIGS. 10 and 11 so as to cause the sheet wrapping material 56 to shrink and so as to cause the overlapping layers 57 to seal together. Upon depression of the handle 4-3 of the suction apparatus, pressure will be applied to the superimposed layers 5% and 55; and when the hot water flows thereover, they will seal together. Thus a commercial package of attractive appearance will be provided which is substantially free from air and is effectively sealed against the re-entry of the air.

Different shape packages may also be wrapped and substantially evacuated by means of my invention. Thus in FIG. 9, I have shown a package for a load, such as a meat loaf, in which a band or label 65 has been extended around the center of the package. The label is made of or is coated with a material which will seal to the outer sheet of wrapping material when heat and pressure are applied thereto. The entire package and label are encased in an outer sheet of wrapping material 66 made of similar material to the sheet wrapper used in the first two forms of my invention. In this instance the sheet of wrapping material is wrapped around the package contents so that longitudinal edge portions thereof are arranged in overlapping relationship across the bottom of the package as shown at 67 and the projecting ends of the material are twisted together as shown at 68. Spaced edges resulting in proximately-spaced air passages are provided in the label 65 and the superimposed layers of wrapping material. These edges and air passages may take the form of an aperture 69 in the label and a spaced aperture 70 formed in the overlapping layer of wrapping material. After the label and wrapper have been wrapped around the packages as shown in FIG. 9, the lower end of suction apparatus is applied to the overlapping layers of wrapping material and label in a confined area encompassing the two apertures as indicated by the dotted line 28, with the result that the air from inside the package is withdrawn therefrom. By extending the band or label 65 around the center of the package, I find that I am able to withdraw a substantial proportion of all of the air from all portions of the interior of the package. The label provides a path through which the air may travel and prevents the pocketing of the air in any portion of the package. After the air has been withdrawn in this fashion, heat may be applied to the packaging material by immersing it in water as shown in FIGS. 10 and 11 with suction apparatus still applied thereto, with the result that the sheet wrapper will shrink and the overlapping layers 67 seal together. The shrinking and heat also cause the twisted ends 68 to be sealed in closed position. When the handle 43 is depressed, the overlapping layers of wrapper and label in the area of the apertures 69 and 70 will be sealed together, preventing re-entry of the air at this point.

Under certain circumstances, I desire to employ my invention in connection with packages in which the wrapper does not shrink when subjected to heat. Thus in FIGS. 7 and 8, I have shown a package having package contents with a label or reinforcing board 75 applied to one surface thereof. The package is encased in two sheets of wrapping material 76 and 77 extending over the upper and lower surfaces respectively of the package and projecting beyond the peripheral edges thereof. The projecting peripheral edges are heat-sealed together in the manner indicated at 78. In this form of my invention the sheet wrapping material 76 and 77 may be any type of flexible sheet wrapping material which can be heat-sealed together regardless of whether it shrinks when subjected to heat, such as thermoplastic material or cellophane or paper coated with a thermoplastic material. The label or reinforcing board 75 likewise should be made of a material which will seal to the wrapping material when heat and pressure are applied thereto, such as fiberboard, cellophane or paper coated with a thermoplastic material.

Spaced edges providing proximately-spaced voids are provided in the superimposed layers. Thus in the label or reinforcing board I provide an aperture 80, and in the overlapping layer of wrapping material I provide an aperture 81. The aperture 81 may be preformed or it may be formed during wrapping as hereinafter explained.

Suction is applied to the overlapping layers in a confined area encompassing the two apertures as indicated in dotted lines at 28. When the air has been withdrawn from inside the package, the superimposed layers are heat-sealed together in the area of the apertures, as indicated by the rectangle 82 in FIG. 7. To accomplish this, I may employ the modified form of suction apparatus shown in FIGS. 18 and 19 in which the casing encloses a vacuum chamber 31 and the orifice 36 is similarly surrounded by a flexible resilient gasket 37. An outlet duct 39 also connects the chamber to a suitable source of vacuum, and a cap 40 encloses the top of the casing and having aperture 41 extending therethrough. In this form of apparatus, however, it is not necessary to separate the vacuum chamber into two separate portions since the package is not submerged in hot water. Accordingly, the handle 43 in this form of apparatus is mounted at the upper end of a modified form of reciproeating rod 85, which is normally held in elevated position by t.e helical spring 86 extending between the handie and the top of the casing. At the lower end of the rod, l mount a heated pressure plate 87, which is preferably insulated from the rod by means of a layer of insulating material, such as fiber glass, asbestos, or the like, indicated at 83. Inside the pressure plate is an electric heater 89 connected by lead wires 90 to a suitable source of electric current. The lead wires extend through a duct in the handle indicated at 91 and a suitable seal 92 is provided in this duct to prevent the air from being sucked therethrough when the apparatus is in use. A thermostatic control or a rheostat (not shown) may be provided for controlling the temperature of the heater.

A suitable guide bracket 93 is mounted inside of the casing as by screws 94 to provide support and to guide the rod 85 as it is reciprocated. A sleeve 99 encases the lower part of rod 85 and serves as a valve for aperture 41. The spring 86 normally holds the rod in elevated position with the heated pressure plate disposed inside the vacuum chamber and with sleeve 99 closing aperture 41. When the handle 43 is pressed downwardly, the valve is opened and the pressure plate 87 is shifted downwardly into engagement with the surface of the package so as to heat-seal the superimposed layers of packaging material together in the area of the voids or apertures, thereby preventing re-entry of air into the package.

As previously indicated, the aperture 81 may be preformed in the packaging material prior to wrapping the package or it may be formed during the packaging process. For this purpose I may provide a heated piercing pin 95 in the suction apparatus for piercing the outer layer of sheet wrapping material and providing a void or aperture therein. The piercing pin 95 in the illustrated embodiment is fixedly mounted on a bracket 96 extending across the guide 93, and the lower end of rod 85 is of bifurcated construction as shown at 97 so as to accommodate the bracket 96. The pin 95 extends through the hot plate 87 and is heated by conduction. The lower end of the pin is spaced a short distance above the peripheral edge of the gasket 37. Thus when the apparatus is applied to the overlapping layers of wrapping material of the package, the wrapper 77 will be drawn upwardly by suction inside the vacuum chamber as shown in FIG. 12, causing the piercing pin to pierce the layer of wrapping material forming aperture 81 therein. When thermoplastic wrapping material is employed, the piercing pin will fuse the wrapper to form the aperture and when nonthermoplastic material is used, the piercing pin will rupture the wrapper. This will insure the proper location of the aperture 81 with respect to the other air passage or aperture 80.

From the foregoing, it will be seen that in each of the illustrated embodiments of my invention I have provided overlapping layers of packaging material having proximately-spaced edges and air passages; and that by applying suction in a confined area encompasing the air passages, the air or a substantial proportion thereof inside the package can be withdrawn through the inner air passage between the layers and outwardly through the outer air passage. It will also be seen that in the completed package the overlapping layers are sealed together in the area of the air passages to prevent re-entry of the air into the package. It will also be seen that I have provided improved apparatus which is useful in evacuating the package and in sealing the overlapping layers together.

It will be appreciated that the drawings merely show illustrative embodiments of my invention and that numerous changes may be made in the illustrated embodiments within the scope of my invention. Thus as previously indicated, one or both of the spaced edges and air passage may simply constitute the end edges of the overlapping layers of packaging material-either sheet wrapping materials or labels, as for instance in the man ner shown in FIG. 5. Also the wrapping material may be wrapped, closed and sealed around the packages specifically at the end portions thereof, in any desired manner. The specific shapev and form of the various embodiments of my invention may also be varied and changed.

Thus the vacuum chambersin the various forms of suction apparatus used for withdrawing air from inside the package need not be circular in cross-sectional shape but may be of any desired cross-sectional shape. Similarly the push bars used for separating the package from the vacuum chamber have been illustrated as being of U- shape, and it should be appreciated that the push bars may likewise be of other desired shapes.

I claim:

1. The method of packaging package contents in sheet material so that the package is at least partially evacuated which comprises: first providing a sheet of wrapping material of the type which shrinks when subjected to heat and which seals together when heat and pressure are applied thereto and which is of greater length than the length of the package contents and of greater width than the distance around the package contents; then wrapping the sheet material around the package contents so that the ends of the wrapping material project beyond the ends of the package contents and so that the longitudinal marginal portions are in overlapping relationship with proximately spaced air passages for the respective overlapping layers arranged in oitset relationship with respect to each other and affording communication between the two surfaces of each of the respective layers; closing and heat sealing the projecting ends of the wrapping material; isolating and confining an area of the overlapping layers and encompassing both of said air passages and applying suction to the outer surface of the confined area of said overlapping layers so as to separate the layers in said confined area from each other and from said package contents and so as to withdraw entrapped air from inside the package through the air passage of the inner layer, thence between the layers and out through the air passage of the outer layer; and finally while continuing to apply suction thereto sealing the confined area of the overlapping layers together by applying heat and pressure to said area so as to prevent the re-entry of air into said package through the air passages and simultaneously applying heat to the remainder of the wrapping material sufiicient to cause it to shrink and thereby eliminate wrinkles and cause it to tightly embrace the package contents and to cause an adhesion between and sealing of the overlapping layers outside of the confined area.

2. The method of packaging package contents in sheet material so that the package is at least partially evacuated It) as set forth in claim 1 in which the air passages are apertures extending through the respective layers.

3. The method of packaging package contents in sheet material so that the package is at least partially evacuated which comprises: first providing a sheet of wrapping material of the type which seals together when heat and pressure are applied thereto and which is of greater length than the length of the package contents and of greater width than the distance around the package contents; then wrapping the sheet material around the package contents so that the ends of the wrapping material project beyond the ends of the package contents and so that the longitudinal marginal portions are disposed in overlapping relationship with proximately spaced air passages for the respective overlapping layers arranged in relationship with respect to each other and affording communication between the two surfaces of each of the respective layers; closing and heat sealing the projecting ends of the wrapping material; isolating and confining an area of said overlapping layers encompassing both of said air passages and applying suction to the outer surface of said overlapping layers in the confined area so as to separate the layers in said confined area from each other and from said package contents and so as to withdraw entrapped air from inside the package through the air passage of the inner layer, thence between the layers and out through the air passage of the outer layer; and finally while continuing to apply suction thereto sealing the confined area of the overlapping layers together by applying heat and pressure to the overlapping layers in said area to prevent re-entry of air into said package through the air passages and simultaneously causing an adhesion between and sealing of the overlapping layers outside of said confined area.

References titted in the file of this patent UNITED STATES PATENTS 1,970,193 Riebel Aug. 14, 1934 2,241,943 Berch May 13, 1941 2,449,272 Berch Sept. 14, 1948 2,545,243 Rumsey Mar. 13, 1951 2,546,721 Campbell Mar. 27, 1951 2,563,316 De Sylva Aug. 7, 1951 2,635,742 Swartz et al Apr. 21, 1953 2,708,541 Jones May 17, 1955 2,778,173 Taunton Jan. 22, 1957 

